Efficient p–n Heterojunction Construction in Co3O4/Zn0.4Cd0.6S Composite for Boosted Visible-Light Photocatalytic H2 Production

In photocatalyst design, constructing p–n heterojunctions is a highly effective way to suppress photogenerated charge recombination and enhance photocatalytic activity. In this study, a precious-metal-free Co3O4/Zn0.4Cd0.6S p–n heterojunction composite was prepared using a facile solvothermal approach. The photocatalytic activity and long-term stability are significantly promoted by the introduction of Co3O4. The composite containing 4 wt% Co3O4 demonstrates a maximum H2 generation yield of 56.63 mmol g−1 h−1, which represents a 6.8-fold improvement over pristine Zn0.4Cd0.6S, significantly surpassing many comparable photocatalysts and even exceeding that of some noble-metal-modified composites. The apparent quantum efficiency (AQE) of 4 wt%-Co3O4/Zn0.4Cd0.6S reaches up to 21.86% at 420 nm. Systematic characterization reveals that the photocatalysts’ p–n heterojunction underlies the remarkable improvement in activity and durability of the composite through facilitated separation and migration of photoinduced electrons and holes. The p–n heterojunction-driven charge separation enhancement fundamentally underpins this significant performance leap. These findings demonstrate a promising approach for developing cost-effective, high-activity photocatalysts for sustainable energy applications.